2,679 research outputs found
An Analysis Framework for Mobility Metrics in Mobile Ad Hoc Networks
Mobile ad hoc networks (MANETs) have inherently dynamic topologies. Under these difficult circumstances, it is essential to have some dependable way of determining the reliability of communication paths. Mobility metrics are well suited to this purpose. Several mobility metrics have been proposed in the literature, including link persistence, link duration, link availability, link residual time, and their path equivalents. However, no method has been provided for their exact calculation. Instead, only statistical approximations have been given. In this paper, exact expressions are derived for each of the aforementioned metrics, applicable to both links and paths. We further show relationships between the different metrics, where they exist. Such exact expressions constitute precise mathematical relationships between network connectivity and node mobility. These expressions can, therefore, be employed in a number of ways to improve performance of MANETs such as in the development of efficient algorithms for routing, in route caching, proactive routing, and clustering schemes
Peterson, L. (1995). Stop and think learning: A teacher’s guide for motivating children to learn: including those with special needs. Camberwell, Victoria: The Australian Council for Educational Research.
Epigenetic Profiling Reveals a Developmental Decrease in Promoter Accessibility During Cortical Maturation in vivo
Axon regeneration in adult central nervous system (CNS) is limited in part by a developmental decline in the ability of injured neurons to re-express needed regeneration associated genes (RAGs). Adult CNS neurons may lack appropriate pro-regenerative transcription factors, or may display chromatin structure that restricts transcriptional access to RAGs. Here we performed epigenetic profiling around the promoter regions of key RAGs, and found progressive restriction across a time course of cortical maturation. These data identify a potential intrinsic constraint to axon growth in adult CNS neurons. Neurite outgrowth from cultured postnatal cortical neurons, however, proved insensitive to treatments that improve axon growth in other cell types, including combinatorial overexpression of AP1 factors, overexpression of histone acetyltransferases, and pharmacological inhibitors of histone deacetylases. This insensitivity could be due to intermediate chromatin closure at the time of culture, and highlights important differences in cell culture models used to test potential pro-regenerative interventions
On the minimum number of neighbours for good routing performance in MANETs
In a mobile ad hoc network, where nodes are deployed without any wired infrastructure and communicate via multihop wireless links, the network topology is based on the nodes’ locations and transmission ranges. The nodes communicate through wireless
links, with each node acting as a relay when necessary to allow multihop communications. The network topology can have
a major impact on network performance. We consider the impact of number and placement of neighbours on mobile
network performance. Specifically, we consider how neighbour node placement affects the network overhead and routing delay.
We develop an analytical model, verified by simulations, which shows widely varying performance depending on source node speed and, to a lesser extent, number of neighbour nodes
Decision region approximation by polynomials or neural networks
We give degree of approximation results for decision regions which are defined by polynomial and neural network
parametrizations. The volume of the misclassified region is used to measure the approximation error, and results for the degree
of L1 approximation of functions are used. For polynomial parametrizations, we show that the degree of approximation is at
least 1, whereas for neural network parametrizations we prove the slightly weaker result that the degree of approximation is at least r, where r can be any number in the open interval (0, 1)
Capitalizing on incentives: Training and certification of dairy traders as a pathway to better milk, health and nutrition
Gender and educational leadership in England: a comparison of secondary headteachers' views over time
In the context of gender being a barrier to accessing leadership, this paper presents a comparison of the views of men and women head teacher (principals) of secondary schools in England in the 1990s and in 2004. The same survey instrument was used on both occasions. The perceptions of the head teachers show change in some areas and no change in others. Overall, women are more likely to become head teachers and are now less likely to be categorised into pastoral roles, but in some cases women still meet prejudice from governors and others in the wider community. Women head teachers are more likely to have partners and children than in the 1990s, sharing equally or carrying most of the domestic responsibilities, whereas male colleagues are most likely to have partners who take the majority of responsibility in the home. Essentialist stereotypes about women and men as leaders still prevail, although both the women and men head teachers see themselves as adopting a traditionally ‘feminine’ style of leadership. Women head teachers are likely to see some benefits in being a woman in a role stereotypically associated with men. However, there has been an increase in the proportion of women who feel that they have to prove their worth as a leader, and this may be linked with increased levels of accountability in schools
The Impact of a Civic Service Program on Biopsychosocial Outcomes of Post 9/11 U.S. Military Veterans
Volunteering as a health promotion intervention, improves physical health, mental health, and social outcomes particularly in older adults, yet limited research exists for veterans. We conducted a preliminary study to explore whether volunteering impacts a variety of biopsychosocial outcomes, including symptoms of post-traumatic stress disorder (PTSD) and depression, among returning military veterans from Iraq and Afghanistan. A survey enrolling a prospective cohort of United States (U.S.) veterans who served in the military after 11 September 2001 and who participated in a national civic service program was conducted. A total of 346 veterans completed standardized health, mental health, and psychosocial self-report measures before and after the program. Statistically significant differences were detected in overall health rating, level of emotional difficulty, PTSD and depression symptoms, purpose in life, self-efficacy, social isolation, and the perceived availability of social support at program completion. Screening positive for probable PTSD predicted improved perceived self-efficacy while probable depression predicted a decrease in loneliness, an increase in purpose in life, and an increase in perceived social support, at program completion. Volunteering was associated with significant improvements in health, mental health and social outcomes in returning veterans
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